6a)Soil can be defined as the organic and inorganic materials on the surface of the earth that provide the medium for plant growth.

6bii Clay soils with 25-40% clayThese soils have a good ability to transport water bycapillary action from deep layers but the rate is slow, so plant water requirements are not met through capillary water.2 These soils are darker in colour and soil aggregation is more distinct.============

8)a) *Causes of Desert Encroachment*1. Human activities: such activities such as over-grazing, over-cultivation, bush burning, and excessive cutting of firewood greatly reduce the vegetative cover and expose the land to drought and desertification. Examples of areas with desert encroachment are the Sahelian zones of Nest Africa, Ethiopia, Somalia and Sudan.2. Change in Weather: The frequent and prolonged dry weather increases the aridity of affected areas.3. The southward movement of the dry sub-tropical high pressure belt results in severe drought in semi-arid regions.

b) *Effects of Desert Encroachment*1. Large scale disruption of socio-economic life arising from crop failure and shortage of water and pasture for livestock.2. Widespread malnutrition and diseases such as kwashiokor and marasmus.3. Migration of people from drought areas to more humid areas.4. Large refugee population, that are made up of victims of drought and social insecurity in the semi-arid areas.5. Disruption of ecological balance and loss of vegetation, soil and water resources.

c) *Preventive Measures of Desert Encroachment*1. Conservation of existing vegetation through legislation against indiscriminate exploitation and felling of forests and trees.2. Legislation and strong control against bush burning.3. Improved grazing practices.4. Establishment of shelter belts to protect the soil and arrest the effect of desertification.5. Afforestation programs.6. Integrated rural development.Factors that affect Mass MovementIt is very clear, that mass movement or mass wasting is movement of weathered material with the aid of gravity, there are many factors that affect this movement. I shall tell you about 6 main factors as follows:1. Where permeable rocks alternate with impermeable rocks, the permeable rocks are more more prone to mass wasting than the impermeable rocks.2. Mass movement is pronounced in areas with steep slopes where the weathered layer is deep and the weathered materials are loose. Naturally, the rate of movement of weathered materials is faster on steep slopes than on gentle slopes.3. Mass movement is encouraged if there are earthquakes and volcanic eruptions.4. Areas with a high annual range of temperature and a high frequency of freezing and thawing will encourage soil creep while areas with a high temperature and occasional torrential rainfall encourage mudflow.5. Mass movement is also encouraged if there is no vegetation.6. The activities of man like mining and herding of animals encourage the production of mass movement or mass wasting. This are the factors that affect Mass movement or wasting.==============

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